<!--[if gte mso 9]> Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 <!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin-top:0in; margin-right:0in; margin-bottom:10.0pt; margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoPapDefault {mso-style-type:export-only; margin-bottom:10.0pt; line-height:115%;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!--[if gte mso 10]> The information on this website has been incredibly educational, but there’s one thing I haven’t run across yet, maybe because it’s too basic.

<!--[if gte mso 9]> Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 <!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin-top:0in; margin-right:0in; margin-bottom:10.0pt; margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoPapDefault {mso-style-type:export-only; margin-bottom:10.0pt; line-height:115%;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!--[if gte mso 10]> Background:  I’m in the early stages of planning a house in southeast Tennessee (Chattanooga area) and have a very basic question.  I will definitely go with SIPS or ICS, so I will need an air-to-air exchanger for ventilation.  I had planned on using radiant heat in the floor, possibly solar with a boiler or electrical backup.  Due to the summer heat I will have to have air conditioning, and have been looking into the mini-split systems.

<!--[if gte mso 9]> Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 <!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin-top:0in; margin-right:0in; margin-bottom:10.0pt; margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} .MsoPapDefault {mso-style-type:export-only; margin-bottom:10.0pt; line-height:115%;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!--[if gte mso 10]> My question:   Do I need to have a duct system for the house in order to move the ‘new’ air from the exchanger around?  If so, doesn’t that push me toward a conventional HVAC system rather than the radiant heating with a mini-split system?  Am I missing something?

Thanks for any help you can give!

Roger

I can't really answer, but I can add to your questions because I looked into the mini-splits too. Do you plan on only needing AC in one spot? Because a mini-split system, if I understand it correctly, is used sort of the way a window unit is used, or one of those spot units in a hotel room. Did you plan on having several mini-split end units? Or maybe your summers are mild enough that one or two units would suffice for the whole house?

I guess I should have been more specific - thanks for asking!  I'm looking at several mini-split units so it would work much like zoned AC.

Roger

I don't think you need ductwork to use the exchanger, but eventually someone more knowledgeable than me will come along here with an answer.

Eliminating the ductwork is appealing with regards to dust and mold, not to mention the cost of the ductwork and its placement. And zoning the AC of course could cut energy usage. I'm just trying to figure out if it's practical, at least for my situation.

Let's say it's August and there are three occupied bedrooms in the house, each with a closed door at night. Would each bedroom need to have its own unit?

The below is from a Life Breath HRV at http://www.lifebreath.com/en/_dat/documents/residential.hrv/ti84rne.pdf

In homes without a forced air furnace, fresh air should

be supplied to all bedrooms and living areas, excluding

bathrooms, kitchen and utility areas. It should be

supplied from high wall or ceiling locations. Grilles that

diffuse the air comfortably such as the Techgrille™

are recommended.

If the floor is the only option available, then special

care should be taken in locating grilles. Areas such as

under baseboard heaters will help to temper the air.

Also optional inline duct heaters are available for

mounting in the supply duct work to add heat if

required.

In homes with a forced air furnace, you may want to

connect the HRV/ERV to the furnace ductwork (see

information below).

Hi Roger, I am not an HVAC expert, but I think the answer to your question is: It depends.

First, I do not believe that it is an absolute requirement that you have an HRV in a SIP or ICF house. My position on this is that it depends on how tight the house is, how many people live in the house and their habits. If you have 2 adults and several kids as well as animals, you will be opening doors enough to let in a lot of fresh air at any time of year. I would suggest that when you build the house, install the external ducts for the HRV and cap them off. Also run the electrical line to the possible future location of the HRV. These things are cheap to do initially and they allow you to easily add the HRV if you find it is required.

Secondly, without information as to the configuration and size of your proposed home, I do not think anyone will be able to give you a very good answer regarding the mini-split option. If you are talking about a large home with multiple rooms, then several mini-split systems might be expensive. You will need to discuss this with your HVAC guy. On the other hand, if the home will have a basement, then the HVAC system and the ducting can be easily located there, inside the building envelop. This also allows you to easily incorporate the HRV if needed.

You can have a conventional AC system with radiant heat. This option would probably cost more than the standard system, but some people want radiant heating for the comfort and energy efficiency it provides. Radiant also allows you to have a floor with thermal mass that can benefit from passive solar gain as well as being able to incorporate active solar heating at some point if desired.

A "mini split" is a air source heat pump, so you get heating and cooling.   Some heat pumps also have the ability to make hot water for radiant heating.  You are in a temperate climate, so a heatpump (air source or ground source) is a viable option. with back up heat  There are two basic types of heat pumps:

Ductless - In this configuration (the true "mini split", which is becoming a generic term for modern heat pumps), the evap unit typically mounts on the wall and has a self contained fan.  These are useful in retrofitting air conditioning or providing it to a room or two, although you could do each room if you wanted to.  The downside to the wall mounted units are aesthetics. The mini splits can support several interior units with one outdoor compressor/condensor.  They are usually very quiet and do a good job.  I have Daikin units in my flat in Italy and like them very much.  We have radiator heating, but the codes permit heating for a limited number of hours per day, so I use the heat pumps to supplement the radiators when it is cold.

Ducted - Same principle as a normal furnace except heat pumps may require larger ductwork than a normal furnace because the heating air temps are lower for a heat pump....not a problem if you do radiant.

If you have a ducted system, I would tie the heat exchanger to the return air system.  Even if the furnace is not running, it will do its job as long as the ERV is runnning.  If you go ductless, I would put a central supply and return on each floor.

If you have a very tight house, I think an ERV or HRV is a very good idea.

Bruce

Bruce,
Mini Splits are not all Heat Pumps? BSIRA reported world shipments of Minisplit/ductless splits are as follows

Cooling Only 2007 = 13,879,298 2008 = 15,066,619
Heatpumpw 2007 = 30,265,777 2008 = 32,683,272

Than makes sense, of course.  While I have never seen a cooling only mini split, there probably is not much call for heating in the tropics, where virtually all of the cooling is done with "mini splits".  Are cooling only units offered in the USA?

Bruce

Yes, any of the major players make both. Media, Gree, LG. You can get some very low cost units on ebay. They can be better than a window but in most cases you get what you pay for..